Previous research in this laboratory has produced separation of functionally distinct populations of bone cells which could be maintained in primary culture. We have recently developed techniques for isolating long-term established cell line from these primary bone cell cultures. This application proposes experiments designed to isolate a series of established, clonal bone cell lines and to characterize the biochemical and functional aspects of these cells. Bone cell lines will be established by spontaneous transformation, mutagenesis or hybridization of primary bone cells, followed by cloning and maintenance of the isolated cells. The established lines will be screened for hormone responses and other bone cell functions and the biochemical basis of these functions will be examined. These experiments will be used to establish a battery of functional markers for bone cell identification in other systems. The isolated bone cell lines will also be used to provide antigens for the development of monoclonal antibodies against specific bone cell markers, using in vitro hybridization of lymphocytes activated by bone cell antigens. These functional and antigenic markers for bone cells will be used to examine the differentiation of both established cell lines and primary bone cells in systems allowing development of bone cells in vitro and in vivo. These experiments will lead to a more specific understanding of the origins and functional development of individual bone cell populations during the processes of bone formation and resorption in normal and diseased conditions.